This invention relates to integrated circuit package handling systems, and more particularly, to a picker nest design that minimizes stress on an integrated circuit component while the picker nest is holding an integrated circuit package within an integrated circuit testing system.
For distribution, an IC (Integrated Circuit) die is mounted within an IC (Integrated Circuit) package. Within such a package, metal leads connect contact pads within the IC die to pins on the IC package. Such pins provide connection from the IC die to other components external to the IC package. To ensure proper packaging of the IC die, the IC package having the IC die mounted thereon is tested. In such testing, the pins on the IC package are coupled to test contacts of a testing system, and various measurements are performed from the test contacts to determine proper IC packaging.
An example of a IC package handler, within an integrated circuit testing system, is the Delta Flex Test Handler, Model 1240, available from Delta Design, Inc., San Diego, Calif. Referring to FIG. 1, such an IC package handling system 100 includes an input mechanism 102, a core unit 104, and an output mechanism 106. The input mechanism 102 carries the IC packages to be tested into the core unit 104 and onto a storage boat 108, already carrying IC packages 110 and 112 in FIG. 1. The storage boat 108 carries the IC packages 110 and 112 until the IC packages reach a desired temperature for testing.
At that point, a core picker assembly 114 picks up an IC package from the storage boat 108 for testing. The core picker assembly includes a picker body 116 and a picker nest 118. The core picker assembly 114 picks up and holds an IC package from the storage boat 108. The core picker assembly then moves the IC package to test contacts 120 such that pins on the IC package make contact with the test contacts 120 for testing of the IC package. The core picker assembly 114 also holds the IC package to the test contacts 120 during testing. The core unit 104 also includes a temperature control unit 122 for adjusting the temperature within the core unit 104 such that the IC package may be tested for various environmental temperatures.
Once the testing of an IC package is complete, the output mechanism 106 includes an output boat 123 which receives the tested IC packages from the core picker assembly 114 after testing and which carries the tested IC packages to a sorting unit 124. When a tested IC package is at the sorting unit 124, each IC package is sorted into a respective bin depending on the results of testing that IC package within the core unit 104. For example, if the result of testing an IC package is performance failure, that IC package is placed into a xe2x80x9cbad chipxe2x80x9d tube 126, and if the result is performance success, the package is placed into a xe2x80x9cgood chipxe2x80x9d tube 128.
Referring to FIGS. 2A and 2B, the conventional core picker assembly includes a picker nest 200 having a picker head 202 with a single suction cup 204 for picking up and holding an IC package to the test contacts 120 of FIG. 1 during testing. FIG. 2B is a bottom view of the picker nest 200 of FIG. 2A. Such a picker nest with a single suction cup is sufficient for picking up and holding an IC package which has a molding covering the IC die that is mounted on the IC package.
Referring to FIG. 3, such an IC package 300 includes an IC die 302 mounted on a package substrate 304. A molding 306 covers and protects the IC die 302. The suction cup 204 would contact the molding 306 when the core picker assembly is picking up and holding the IC package 300 to the test contacts 120 for testing.
However, IC packages are available in a variety of sizes, shapes, and configurations. For example, the CBGA (Ceramic Ball Grid Array) 360 which is used for packaging the K6 Microprocessor from Advanced Micro Devices, Inc., Santa Clara, Calif., may need testing with a packaging configuration as shown in FIGS. 4A and 4B.
Referring to FIG. 4A, the CBGA 360 package 400 that may need testing includes a bare IC die 402 mounted on a first surface 404 of a ceramic package substrate 406. Capacitors 408, 410, 412, 414, 416, and 418 may be included for coupling to the IC die 402. FIG. 4A shows the first surface 404 of the CBGA 360 package. FIG. 4B shows a second surface 420 of the CBGA 360 package. This second surface 420 includes a grid array 422 of substantially spherical balls that are package pins which couple to circuit pads within the IC die 402. The CBGA 360 package includes a grid array of 19 rows by 19 columns of ball pins. However, the grid array 422 of 4 rows by 4 columns of ball pins is shown in FIG. 4B for clarity of illustration. This grid array of ball pins 422 makes contact with the test contacts 120 of FIG. 1 during testing.
Because of the bare IC die 402 mounted on the package substrate 406, a conventional picker nest 200 with the single suction cup 204 of FIG. 2A may apply unacceptable stress on the die 402 when the core picker assembly is picking up or holding the CBGA 360 package for testing. Moreover, a suction cup of the prior art which typically includes a plastic O-ring or a sponge may not sufficiently seal in the vacuum within the suction cup during testing at lower temperatures such as 0xc2x0 Celsius to xe2x88x9255xc2x0 Celsius (or below). However, a package configuration, such as the CBGA 360 package, which includes a bare IC die may be desirable for some integrated circuits, and such a package may still need testing at various temperatures.
Accordingly, a primary object of the present invention is to pick up and hold such an IC package having a fragile integrated circuit component, such as a bare IC die, mounted thereon without inducing unacceptable stress on the fragile component during IC package testing at various temperatures.
In a general aspect of the present invention, a picker nest which holds the IC package for testing includes a picker nest head having a picker nest opening with vacuum suction for holding the IC package. The dimensions of the picker nest opening are larger than the dimensions of the fragile component such that the fragile component fits within the picker nest opening when the picker nest is holding the IC package. In addition, a conductive seal disposed on the picker nest head and disposed outside the perimeter of the picker nest opening seals the vacuum suction within the picker nest opening.
Furthermore, at least one supporting bar disposed on the picker nest head supports the package substrate against the picker nest head when the picker nest is holding the IC package.
The present invention can be used to particular advantage when the picker nest head and the at least one supporting bar are comprised of aluminum. In that case, the picker nest head and the supporting bar provide ESD (Electro Static Discharge) protection for the IC package during testing. The conductive seal which seals the vacuum suction within the picker nest opening may be a silicon-based sponge to ensure sufficient vacuum seal at lower temperatures.
Such a picker nest does not induce contact force on the fragile component mounted on the IC package since the fragile component fits within the picker nest opening when the picker nest is holding the IC package. Thus, the present invention is particularly amenable for holding an IC package such as the CBGA 360 package that has a bare IC die mounted on the package substrate.
These and other features and advantages of the present invention will be better understood by considering the following detailed description of the invention which is presented with the attached drawings.